1. Field of the Invention
The present invention is directed to surface cleaning equipment, and more particularly to a braking mechanism for surface cleaning equipment.
2. Background
Surface maintenance vehicles and cleaning devices have a long history subject to gradual innovation and improvement toward improved and oftentimes automated performance in removing debris and contamination from floors. These vehicles and devices may be self-powered, towed, or pushed, and/or manually powered and may carry a human operator during cleaning operations. Such vehicles and devices include scrubbers, extractors, sweepers and vacuums, as well as combinations thereof, intended for cleaning, scrubbing, wiping and/or drying a portion of a substantially flat surface both indoors and outdoors.
A class of surface maintenance vehicles, known as riders, may contain an operator that drives the vehicle, using controls functionally similar to those in an automobile, including a steering wheel, an accelerator pedal and a brake pedal. As in an automobile, the accelerator and brake speed up and slow down the vehicle, but because the motor in a rider vehicle is typically electric, the methods by which the accelerator and brake function are usually quite different from those in an automobile.
The braking on a typical rider surface maintenance vehicle is generally accomplished in a mechanical manner, using a brake cable to transmit a force from the brake pedal to one or more brake pads. Although a mechanical brake assembly provides the operator with a comfortable “feel” for braking, it is relatively expensive. A significant cost savings would be realized if the mechanical braking assembly were eliminated. Note that for safety concerns, it is not feasible to eliminate the brake pedal on a rider surface maintenance vehicle. (In contrast, a walk-behind machine may function without an additional brake, because the speeds are much less and the machines may be much smaller.)
For safety reasons, a rider surface maintenance vehicle usually has a mechanical brake, typically in the form of a spring-loaded caliper brake pad, which is often referred to as a parking brake, which may or may not share a mechanism with the mechanical brake described above. Generally, the parking brake may be activated electronically by a solenoid, so that if the current to the solenoid is shut off, as may occur during a failure mechanism, then the parking brake is engaged. The use of a solenoid-activated spring-loaded caliper brake as a parking brake is well-known in the art. In addition, it is common to engage the parking brake when the accelerator pedal is released, when the vehicle velocity drops below a threshold value.
Accordingly, there exists a need for a braking mechanism that costs less than a mechanical assembly, but still provides the operator with a proper braking “feel”, and stops the vehicle in the event of a malfunction. Thus, since most operators are already familiar with the feel of a mechanical braking system, designing an electrical system which proximates (mimics) that feel is highly desirable.